<style>
    * {padding:0px;margin:0px;}
    .box {
        width:500px;
        height:180px;
        overflow: hidden; 
        position: relative;
    }
    ul {
        list-style:none;
        position: absolute;
        bottom: 10px;
        left: 50%;
        margin-left: -60px;
    }
    ul li {
        float: left;
        width: 10px;
        height:10px;
        background: #fff;
        border-radius: 50%;
        margin-right: 10px;
    }
    ul li.active {
        background: blue;
    }
</style>

<div class="box">
    <img src="./imgs/img1.jpg" alt="">
    <ul>
        <li class="active"></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
        <li></li>
    </ul>
</div>

<script src="./json.js"></script>
<script>
    let obj1 = new Preson('.box')
</script>
